package com.geek.gkpush.util.http;

import org.apache.commons.lang3.StringUtils;

import javax.servlet.http.HttpServletRequest;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

/**
 * <h1>Header相关处理工具类。</h1><br/>
 *
 * <h1><br/><a href="https://u.geekbang.org/subject/arch3/100614201">Java 业务架构实战营：https://u.geekbang.org/subject/arch3/100614201</a></h1><br/><h1><a href="https://gitee.com/ylimhhmily/BizArchPracticeCamp">Java 业务架构实战营代码地址：https://gitee.com/ylimhhmily/BizArchPracticeCamp</a></h1><br/><h1><a href="https://u.geekbang.org/subject/java4th/1001148?source=app_share">高级 Java 工程体系课 2023 版：https://u.geekbang.org/subject/java4th/1001148?source=app_share</a></h1><br/><h1><a href="https://time.geekbang.org/column/intro/100312101?tab=catalog">Dubbo 源码剖析与实战：https://time.geekbang.org/column/intro/100312101?tab=catalog</a></h1>
 *
 * @author hmilyylimh
 *         ^_^
 * @version 0.0.1
 *         ^_^
 * @date 2022-02-19
 *
 */
public class HeaderUtils {

    /**
     * <h2>解析并获取报文头。</h2>
     *
     * @param request
     * @return
     */
    public static Map<String, Object> parseHeaders(HttpServletRequest request) {
        Map<String, Object> headerParams = new HashMap<>();
        Enumeration<String> enumeration = request.getHeaderNames();
        while (enumeration.hasMoreElements()) {
            String header = enumeration.nextElement();
            String value = request.getHeader(header);
            if (StringUtils.isNotBlank(value)) {
                headerParams.put(header, value);
            }
        }

        return headerParams;
    }

    /**
     * <h2>从 header 里面通过 name 获取对应的 value，这里忽略 name 的大小写去查询 value。</h2>
     *
     * @param headerParams
     * @param name
     * @return
     */
    public static Object getValue(Map<String, Object> headerParams, String name) {
        if (headerParams == null || headerParams.isEmpty()) {
            return null;
        }

        Object val = headerParams.get(name);
        if (val != null) {
            return val;
        }

        for (Map.Entry<String, Object> entry : headerParams.entrySet()) {
            String key = entry.getKey();
            if (key != null && key.equalsIgnoreCase(name)) {
                return entry.getValue();
            }
        }
        return null;
    }
}